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Today, the commercial application of silicon oxides (SiO x , 1 < x < 2) in lithium-ion batteries (LIBs) still faces the challenge of rapid performance degradation. In this work, by integrating hydrothermal and physicomechanical processes, water-soluble locust bean gum (LBG) and xanthan gum (XG) are utilized to in situ form an LBG@XG binder network to improve the performance of SiO x /C anodes. As a synergy of LBG and XG polysaccharides in hydrogel polymerization, LBG@XG can tightly wrap around SiO x /C particles to prevent plate damage. The flexible SiO x /C anode with the LBG@XG binder exhibits capacity retentions of 74.1% and 76.4% after 1000 cycles at 0.5 A g -1 and 1 A g -1 , respectively. The full battery capacity remains stable for 100 cycles at 1 C and the rate performance is excellent (103 mAh g -1 at 3 C). This LBG@XG is demonstrated to be highly electronegative and has a strong attraction to SiO x /C particles, thereby reducing the expansion and increasing the stability of the SiO x /C anodes when coupled with the flexible binder network. In addition to the promising LBG@XG binder, this work also provides a research idea for developing green water-based binders suitable for application in the SiO x /C anodes of LIBs.

1,2,3,4-Tetrakis(2-cyanoethoxy)butane (TCEB) is first evaluated as a functional electrolyte additive to increase the charge cutoff voltage and energy density of pouch LiCO 2 (LCO)/artificial graphite (AG) lithium-ion batteries (LIBs) at a high temperature of 45 °C. The charge (0.7 C) and discharge (1 C) tests show that TCEB effectively improves the cycle stability of cells under a high charge cutoff voltage of 4.5 V. At 25 °C, the capacity retention of the cells with TCEB increases from 0.0% to 72.1% after 1200 cycles. At 45 °C, the capacity retention of the cells without TCEB after 50 cycles is close to 0.0%, while the capacity retention of the cells with TCEB is still 81.6%, even after 350 cycles. The spectroscopic characterization results demonstrate that the TCEB electrolyte additive participates in the construction of a self-repair electrode/electrolyte interface film. Subsequently, low impedance and strong protective layers are formed on the two electrode surfaces. The quantitative analysis results and a theoretical calculation also show that TCEB effectively inhibits the dissolution of Co 3+ and maintains the structural integrity of electrode materials. These results indicate that TCEB endows LIBs with excellent cycle stability and is a promising electrolyte additive for the high-voltage and high-temperature conditions of LCO-based LIBs.

A silicon suboxide-carbon (SiO x /C, 1 ≤ x ≤ 2) composite anode of lithium-ion batteries (LIBs) with enhanced performance is prepared using an aqueous multicomponent binder technology. Considering the adhesive force, electrolyte absorption, and stability, different binders including sodium alginate (SA), polyacrylamide gel (PAM), polytetrafluoroethylene (PTFE), and their composites are evaluated. It is indicated that compared to other anodes with single- or multicomponent binders, the SiO x /C composite anode with PAM/SA/PTFE663 (PSAP663) binders exhibits strong adhesion, moderate electrolyte absorption ability, and a specific capacity of 427 mA h g -1 charge-discharged at 0.5 A g -1 after 300 cycles. The improvement of electrochemical performance is attributed to the comprehensive effects of composite binders, including the adhesion of active substances, surface protection, solution adsorption, conductive path, and so on. These results show that the PSAP663 binder has promising potential for application, which not only gives alternative practical schemes of the green binders for the SiO x /C anodes but also provides ideas to develop a high-performance adhesive technology for LIBs., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Increasing the upper cutoff voltage is capable of achieving higher charge capacity, whereas this strategy always causes a dramatic degradation of cycling and thermal stability. In this study, we first report spinel LiNi 0.5 Mn 1.5 O 4 -modified LiCoO 2 (LiCoO 2 @LiNi 0.5 Mn 1.5 O 4 ) as an outstanding cathode material. LiCoO 2 @LiNi 0.5 Mn 1.5 O 4 retains capacity retention of 81.4% in a full cell between 4.45 and 3.00 V after 400 cycles at 0.5 C and is superior to 55.3% of pure LiCoO 2 . In situ X-ray diffraction at an upper cutoff voltage of 4.75 V in combination with differential capacity curve reveals that the promoted cycling performance is ascribed to a delay of O3 → H1-3 → O1 phase transitions and a suppression of cobalt dissolution-induced side reactions. Moreover, LiNi 0.5 Mn 1.5 O 4 modification improves the thermal stability of LiCoO 2 by depressing the release of oxygen and the formation of cobalt dendrites.

Three-dimensional (3D) rigidity-reinforced SiO x anodes are prepared using the aqueous multicomponent binders to stabilize the performances of lithium-ion batteries. Considering an elastic skeleton, adhesiveness, electrolyte absorption, etc., four kinds of binders [polyacrylamide (PAM), poly(tetrafluoroethylene) (PTFE), carboxymethyl cellulose, and styrene butadiene rubber (SBR)] are selected to prepare aqueous multicomponent binders. The SiO x anodes with the binder PAM/SBR/PTFE (PSP) exhibit a 3D rigidity-reinforced structure, larger adhesive force, and moderate electrolyte adsorption capacity compared to other anodes with single and multicomponent binders. Specifically, the electrochemical performances of the SiO x anodes with the binder PSP663 are stabilized, and a retention capacity of 770 mAh g -1 at 500 mA g -1 after 300 cycles and a rate capacity of 993 mAh g -1 at 1200 mA g -1 are obtained. The enhanced performances are attributed to the good chemical stability of PTFE to protect SiO x particles from the electrolyte corrosion and to ensure electrode integrity. SBR acts as the binder backbone due to the strong adhesion force and specific three-dimensional structure. The rigidity of PAM limits the excessive expansion of SiO x particles well and shortens the ion migration. These results indicate that the 3D rigidity-reinforced SiO x anode with the aqueous binder PSP663 has promising prospects for practical application, and the results also provide a reference for solving the expansion problem of the silicon materials.

An electrolyte using 2,3,4,5,6-pentafluorophenyl methanesulfonate (PFPMS) as a versatile additive is investigated through calculating the molecular orbital energies of additives and solvents and designing the electrolyte composition, and the comparative performances of LiNi 0.5 Co 0.2 Mn 0.3 O 2 /graphite cells operating in a wide-temperature range are improved. It is revealed that PFPMS can form interfacial films on both the cathode and anode surfaces, resulting in a decrease of the cell impedance and the side reactions between the active materials and electrolyte. Compared to the cells without additive of 74.9% and those with vinylene carbonate (VC) of 76.7%, the cycling retention of the cell with 1.0 wt % PFPMS reaches 91.7% after 400 cycles at room temperature. In particular, for the high-temperature storage at 60 °C for 7 d, the cell containing 1.0 wt % PFPMS exhibits optimal capacity retention of 86.3% and capacity recovery of 90.6%; for the low-temperature discharge capacity retention at -20 °C, the cell with 1.0 wt % PFPMS maintains at 66.3% at 0.5 C, while for the cells without additive and containing 1.0 wt % VC, their retention values are 55.0 and 62.1%, respectively. The excellent cycling, wide-temperature practicability, and rate capability of the cells with PFPMS demonstrate that the electrolyte with PFPMS additive is promising for applications in LiNi 0.5 Co 0.2 Mn 0.3 O 2 /graphite batteries.